\documentclass{article}
\usepackage{amsmath}
\begin{document}
\pagestyle{empty}
\[
p = \left\lfloor\frac{4x+3}{4n+1}\right\rfloor \quad
b = \left\lfloor \frac{p(4n+1)}{4} \right\rfloor  \quad
d = x-b
\]
\end{document}
